The invention relates to a radiation diagnostic apparatus for producing transverse layer images of a radiography subject, comprising a patient support, a radiation source which generates a radiation beam penetrating the radiography subject, a radiation receiver which converts the transmitted radiation intensity behind the subject into electric signals, a measured value converter for the conversion of the electric signals supplied by the radiation receiver into an optically visible image, and a rotating frame on which the radiation source and the radiation receiver are mounted and which, for the purpose of scanning the radiography subject from different directions, is rotatably mounted about an axis extending generally parallel to the longitudinal direction of the patient support.
A radiation diagnostic apparatus of this type is described in the German OS No. 25 59 658 (U.S. Pat. No. 4,002,917). This radiation diagnostic apparatus, designated as a computer tomograph, permits the scanning of several parallel layers of the radiography subject. To this end, the elements of the radiation receiver extend in a direction generally parallel to the longitudinal direction of the patient support over the set of layers to be scanned. The X-ray tube exhibits an anode on which a deflectable electron beam activates focal spots at specified locations so that, given corresponding collimation, different layers are irradiated. A different part of the elements of the radiation receiver--viewed in the longitudinal direction of the patient support--is here irradiated with X-rays in each instance. The various focal spots are activated by means of deflection of the electron beam of the X-ray tube.
The known radiation diagnostic apparatus permits, in a very brief time, the scanning of several parallel layers of the radiography subject; however, it is constructed in a very complicated fashion because it requires, in particular, a special X-ray tube.
Also with a computer tomograph, in which a conventional X-ray tube is employed with a focal spot which is stationary relative to the tube, the scanning of several parallel layers of the radiography subject is possible if, subsequent to scanning of one layer, the patient support is displaced in the longitudinal direction and then the next layer is scanned. However, in order to scan several parallel layers, a relatively large amount of time is necessary for this purpose.